I'll keep this short because we are at the middle of this drama so I'll comment on the episodes I've seen so far.
This is going to be the drama of the year for me from Korea. This drama deserves all the hype, all the love and all the support because this is a masterpiece. The story is touching and I hope people can appreciate it. I'm enjoying every single moment because I know when this is going to end, there will be a temporary emptiness. You can always re-watch it but it is not going to be like the first time. Like I said the story is very nice and actually it's more addicting as the episodes go by. LOVE the chemistry between the main characters. The actors are wonderful at doing their job and bringing the character to life. The emotion and passion behind the acting is amazing. Honestly is a pleasure to watch. The characters have depth and purpose. Their development is amazingly done. It's just amazingly written drama. Also from time to time you can find some comedy. You'll laugh and then cry. The side characters are amazing so far, but their story is yet to be told. So far so good.
Production is on point. The music is wonderful. It such a nice drama and I've seen people rating it with 2 stars. Like tf you want more?? These 14 yr girls need to chill...

------EDIT-----

I gave it sometime for everything to settle down so now here is my opinion.
Worth watching. The story was interesting and beautifully done, even thought sometimes it felt like a drag. The character development was nicely done. The cinematography was amazing, and the side characters were good. Loved that there was no love triangle between the two leads, but instead it was between the side characters. I loved the ending. After everything they've gone thru it was nice to see how the story wrapped up. The OST was STUNING. Breaking down's been on repeat for several days now. Such a song.
Please give it a try. Very strong drama.